[gjc11028]

And you really shouldn't be using it if your amp has differential outputs anyways.

Not sure I understand what you are saying

 

[Armaegis]

Most boxes of this sort are simple resistor dividers which tie the grounds together. Most of the time this isn't a problem.
 
The issue is amps that have differential output ("balanced"). Since there's no common ground, if you tie the negatives together you'll blow up the amp. A fuzzy grey area is some amps (usually class D) have "ground" at the negative, but those are kinda floating and aren't necessarily the same across L & R.
 
Some of the converter boxes get around this issue by slapping a pair of resistors between the negatives and making a fake ground in the middle. This protects the amp from blowing up, but doesn't really do any favours for the sound.

 

[davidsh]

In which way does it screw up the sound (aside from worse damping factor)?

 

[Armaegis]

If you're tying the negatives together of a differential amp, you're basically summing them. So now you don't even have a proper difference across the left and right channel. Basically a stupid amount of crosstalk... practically halfway to mono-town. 
 
In the case of ground-but-not-quite negatives (such as with class D, but other topogies too maybe), you're probably going to create a ton of noise, maybe some good 'ol fashioned DC offset, etc.

 

[gjc11028]

  If you're tying the negatives together of a differential amp, you're basically summing them. So now you don't even have a proper difference across the left and right channel. Basically a stupid amount of crosstalk... practically halfway to mono-town. 
 
In the case of ground-but-not-quite negatives (such as with class D, but other topogies too maybe), you're probably going to create a ton of noise, maybe some good 'ol fashioned DC offset, etc.

thanks.  i have an amp that has balanced output (both positive and negative speaker terminals have signal) so i was curious about what you were saying. i have a balanced cable to the headphones and an adapter built by the person who built the amp.  
 
 i was thinking about the woo wee and found i could not use it because of the grounding issue.   (there is a work around if you connect the negative speaker connections to the chassis instead of the negative binding posts, but never got that far)

 

[Armaegis]

Interesting. I had emailed Woo a while ago and got a reply saying that a balanced amp was fine with the WEE.

 

[gjc11028]

  Interesting. I had emailed Woo a while ago and got a reply saying that a balanced amp was fine with the WEE.

 
exchange with woo audio (last year):
 
Gary,
The WEE cannot work with a balanced power amp. Please let me know if I can help any other way.
Thanks
Jack
On Apr 5, 2013 9:02 AM, "gary claxton" <gjclaxton@gmail.com> wrote:

Hi and thanks.  i use separate amps for speakers and headphones now (two outs from preamp) but this would give me another option.  one more question if i may.  one of the reviews i read said that the wee would not work with speaker amps that use a balanced output such as some of the pass labs?  I did not remember seeing that in the manual but i looked quickly.  not an issue for my tube amp but i also have a a blue circle hybrid.  Is this an issue i need to consider?  Blue Circle description is   

All Blue Circle amplifiers* employ true balanced output technology. This means both the positive and negative binding posts supply active signal to the speaker voice coils. The advantage This results in the amplifier applying more control over the speaker cone motion than conventional designs.

  

 

The '200 series amplifiers are the first models to take advantage of the latest design refinements to our balanced output technology. Since the negative binding posts are in fact not grounds as in most other amplifier designs we have included independent chassis /earth grounds on the rear panels of the 200 series amplifiers to accommodate installations that may require the application of a true ground.* 
 
thanks.  i am pretty sure i want to order a wee but thought i should ask about this
 
gary

 

 

[Armaegis]

I got this response from him last year...
 

 A bridged/balanced spk amp can be used for WEE.

Thanks,
Jack
--------------------------
www.WooAudio.com
Twitter.com/WooAudio

 

[Chris J]

If you're tying the negatives together of a differential amp, you're basically summing them. So now you don't even have a proper difference across the left and right channel. Basically a stupid amount of crosstalk... practically halfway to mono-town. 

In the case of ground-but-not-quite negatives (such as with class D, but other topogies too maybe), you're probably going to create a ton of noise, maybe some good 'ol fashioned DC offset, etc.

That's correct, tying the grounds together would, to some extent, defeat the output noise filter.
Don't do it.
Follow the guidelines in the amplifier's owner's manual.

 

[wuwhere]

If you take the positive but tie the negative to ground it should work since you are not using the negative half of the differential amp.

 

[gjc11028]

If you take the positive but tie the negative to ground it should work since you are not using the negative half of the differential amp.

the maker of my amp said that I could connect the negative speaker connections to two wing nuts on the back of the amp and then the amp would be single ended. Never tried it.

 

[gjc11028]

I got this response from him last year...

I think it was the 6moons review which said it could not be used with amps with balanced output like pass labs. That is why I asked. Maybe they changed the design at some point.

 

[Armaegis]

  If you take the positive but tie the negative to ground it should work since you are not using the negative half of the differential amp.

Assuming that there's no DC offset relative to ground (not likely... but you never know sometimes).

 

[wuwhere]

 
Assuming that there's no DC offset relative to ground (not likely... but you never know sometimes).

 
One can measure the DC offset and as long as it is within the acceptable range.

 

[Chris J]

If you take the positive but tie the negative to ground it should work since you are not using the negative half of the differential amp.

Assuming you can tie the headphone common to signal ground, not the safety ground, which may or may not be chassis ground.

Assuming that there's no DC offset relative to ground (not likely... but you never know sometimes).

Whether the output is SE or bridged (balanced, differential), the outputs should have minimum DC offset relative to signal common.
Measure the DC offset to be sure.